Most of man's foods in the natural state are protected with a covering of one kind or another. Examples are the peel tissues of fruits and vegetables, hulls of legume seed pods, shuck covering of corn ears, skins of onions, shells of nuts, scales of fish, and the calcareous coverings of shellfishs. In most cases, these coverings are considered to be unedible and are therefore eliminated when preparing the product for human consumption.